1. Field of the Disclosure
This disclosure relates generally to apparatus and methods for completing a wellbore for the production of hydrocarbons from subsurface formations, including fracturing selected formation zones in a wellbore, packing sand between the formation zones and casing in the wellbore and deploying a production string in the wellbore for the production of the hydrocarbons.
2. Background of the Art
Wellbores or wells are drilled in subsurface formations for the production of hydrocarbons (oil and gas). Modern wells can extend to great well depths, often more than 1500 meters. Hydrocarbons are trapped in various traps in the subsurface formations at different depths. Such sections of the formation are referred to as reservoirs or hydrocarbon-bearing formations or zones. Some formations have high mobility, which is a measure of the ease of the hydrocarbons flow from the reservoir into a well drilled through the reservoir under natural downhole pressures. Some formations have low mobility and the hydrocarbons trapped therein are unable to move with ease from the reservoir into the well. Stimulation methods are typically employed to improve the mobility of the hydrocarbons through the reservoirs. One such method, referred to as fracturing and packing (also referred to as “frac/pack”), is often utilized to create cracks in the rock in the reservoir and pack it with sand to enable the fluid from the formation (formation fluid) to flow from the reservoir into the wellbore. To frac/pack multiple zones, an assembly containing an outer string with an inner string therein is run in or deployed in the wellbore. The outer string is conveyed in the wellbore with a tubing (pipe) attached to its upper end and it includes various devices corresponding to each zone to be fractured for supplying a fluid with proppant to each such zone. The inner string includes devices attached to a tubing to operate certain devices in the outer string and facilitate fracturing and/or other well treatment operations. For selectively treating a zone in a multi-zone wellbore, it is desirable to have an inner sting that can be selectively set corresponding to any zone in a multi-zone well and perform a well operation at such selected zone.
The disclosure herein provides apparatus and methods for treating multiple zones along a wellbore and pack such zones with a proppant to enable efficient to flow of the fluid from the formation to a wellbore.